Japanese Patent Laid Publication Hei 7-209922 discloses an image-forming device using highly viscous and highly concentrated liquid toner developer. For example, FIG. 1 illustrates a liquid toner image-forming device in a block diagram. A feed roller 7 and a pair of register rollers 8 feed a piece of an image-carrying medium such as a sheet of paper into a liquid toner image-forming unit 4 from an image-carrying holding unit 5. The liquid toner image-forming unit 4 includes a photoreceptor drum 1 whose surface is first electrically uncharged by a charge removal unit 10, then cleaned by a cleaning unit 11 for removing residual electrical charge and toner, and electrically charged in a uniform manner by a charging unit 2. An exposing unit 3 generates an electrostatic image on the photoreceptor surface according to a desired image to be duplicated. The electrostatic image is then adjacently positioned to a developer belt 41 which carries a sheet of toner developer and is visualized by toner on the developer belt 41. In other words, toner is selectively transferred onto the photoreceptor surface according to the electrostatic image pattern. The visualized image on the photoreceptor 1 is further rotated towards a transfer roller 9 where the toner is transferred from the photoreceptor surface 1 to an image-carrying medium. A fixing unit 12 stabilizes the transferred toner image. The image-carrying medium with the duplicated image is placed in an output holding unit 13.
Still referring to FIG. 1, in order to prepare a uniformly thin layer of liquid toner developer 43, a series of rollers transfers the liquid toner developer 43 from a toner developer storage unit 44 onto the developer belt 41. The liquid toner developer 43 contains liquid toner as image-forming particles dispersed in insulating liquid developer such as methyl poly-siloxane oil and is highly viscous about 10000 mPa.cndot.s for visualizing the electrostatic image. An application roller 45 is partially submerged in the above described toner developer 43 and rotates in a counter clockwise direction. A squeeze roller 47 rotates together with the application roller 45 in a counter clockwise direction and abuts the application roller 45 to maintain a desired level of the liquid toner developer 43 on the application roller 45. A coating roller 46 is located above the squeeze roller 47 and abuts the application roller 45 while rotating also in the counter clock direction. Thus, a desirable level of the liquid toner developer 43 reaches the coating roller 46.
The developer belt 41 is supported by a plurality of rollers 41a through 41d. The developer belt 41 contacts the coating roller 46 at one end and is juxtaposed to the photoreceptor 1 at the other end. Thus, a layer of the liquid toner developer 43 is formed on the developer belt 41 and is juxtaposed to the photoreceptor drum 1 for selectively transferring a portion of the toner onto the photoreceptor surface according to the electrostatic image via a bias voltage exerted by a bias voltage unit 42 at the supporting roller 41d. On the other hand, the developer or the carrier from the liquid toner developer layer is uniformly transferred onto the photoreceptor surface. After the toner and developer transfer, a belt cleaning blade 48 removes residual liquid toner developer on the photoreceptor belt 41 and collects it in a used toner holding unit 49.
The above-described uniform thin layer of the liquid toner developer is fixedly predetermined regardless of the size of the image-carrying medium. For example, even if a post card is used to print image or text, the thin layer of the liquid toner developer is prepared in a larger size such as A4 size. In other words, since the same set of rollers including the application roller 45, the squeeze roller 47 and the coating roller 46 is utilized in preparing the thin layer of the liquid toner developer, the identically sized thin layer is generated regardless of the ultimate destination size of the image-carrying medium. When the size of the image-carrying medium is smaller than that of the identically sized thin layer, an unused portion of the liquid toner developer corresponding to an area outside the smaller image-carrying medium is wasted. The current invention is addressed at least to reduce the above-described waste of the toner developer.